The present invention encompasses devices which are used in the vagina to deliver spermicidal surfactants. By virtue of their unique construction and shape, the devices herein are foldable for easy insertion. Once in position at the cervical os, the devices open to "cap" the os and remain in position, even during intercourse, so that access of the spermicidal surfactant source to the cervical os is not interrupted.
The devices of this invention are designed for use in the vagina, can be inserted by the user, and do not require insertion by a physician as, for example, in the case of intrauterine contraceptive devices. The devices are designed to remain in the vagina during the time between menstrual periods to provide desirable, prolonged release of a spermicidal surfactant, and their construction and shape facilitate retention therein. An effective between-period contraceptive device is thereby provided.
The devices of the present invention combine the desirable features of devices which provide prolonged release of medicaments, e.g. spermicides, or the like, through a membrane and into the vaginal area with the added advantages that the unique construction and shape of the present devices allow them to be worn comfortably in the vagina for periods of several weeks and to remain substantially undisturbed within the vaginal cavity during sexual intercourse.
For devices to open after insertion and be retained over the cervical os, they need to be stiff enough to maintain their general shape during wear. The necessary stiffness may be provided by incorporating a rim into the devices. While this allows a device to be positioned and retained well, a rim can undesirably cause awareness of the device during wear and during intercourse.
On the other hand, a device that is soft and compliant conforms well to the vagina and also results in minimal awareness during wear or during intercourse. However, if such rimless devices are too soft or compliant, they will not open to cover the cervix in use.
The construction of the present devices allows them to be positioned in the vagina in such a way that maximum contraceptive protection is secured. As can be seen by reference to the figures herein, the highly preferred devices of the present type for use within the vaginal cavity are characterized by a comfortable construction and comprise a container, said container having walls which allow passage of spermicidal surfactant monomers from within the container into the vagina. The configuration of the devices allows them to be placed in the closest possible proximity to the cervical os, and this feature contributes importantly to their contraceptive efficacy. Indeed, the highly preferred devices herein substantially surround and "cap" the cervical os.
By the present invention, comfortable devices which open after insertion into the vagina are manufactured by incorporating reinforcing means across the back of the device. The resulting devices open after insertion, conform well to the vagina, and result in minimal awareness during wear or during intercourse.
The reinforcing means can be arranged to provide the additional advantage of ensuring that spermicide solution in the device has a pathway to that, generally central, portion of the device which lies over the cervix. When a device is worn, it may sometimes be flattened by the cervix and the walls of the vagina. If the face of the device which is toward the cervix is pressed against the back of the device, access of surfactant solution to the semi-permeable membrane is blocked. The reinforcing means can be arranged to provide channels so that even if the membrane is pressed against the reinforcing means on the back, the surfactant solution still has a pathway to that portion of the membrane covering the cervix.
The front and back walls of the present devices comprise polymeric membranes. By using membranes of different thickness, the major part of the contraceptive surfactant agent released from the devices can be directed through the face to the primary situs of contraceptive activity, i.e., to the cervical os, and losses of contraceptive agent by dissipation into the general vaginal area through the back are thereby minimized.
In use, the devices are folded for insertion into the vagina posterior to the introitus such that they are positioned in the closest possible proximity to the cervical os. The reinforcing means in the outer wall of the devices cause them to open from the folded position to substantially block or cap the os.